Gun sight trainer



Nov. 23, 1954 E. M. MCNATT 2,694,869

GUN SIGHT TRAINER Filed Nov. 25, 1949 3 Sheets-Sheet 1 F I I INVENTOR.EUGENE M. McNATT Nov. 23, 1954 E. M. M NATT 2,694,869

GUN SIGHT TRAINER Filed Nov. 25, 1949 3 Sheets-Sheet 2 l [30 M F162JNVENTOR.

; EUGENE M. McNATT ATTORNEY Nov. 23, 1954 E. M. M NATT ,694,

GUN SIGHT TRAINER Filed Nov. 25, 1949 3 Sheets-Sheet 5 INVENTOR.

' EUGENE M. McNATT United States Patent 6 GUN srGr-rr TRAINER Eugene M.McNatt, Tulsa, Okla, assignor, by mesne assignments, to the UnitedStates of America as represented by the Secretary of the NavyApplication November 25, 1949, Serial No. 129,217

9 Claims. (Cl. 35-25) This invention relates to a means for impartingangular motion to an apparatus, and for controlling said motionindependently of the supporting framework of the apparatus.

More specifically, the invention relates to an apparatus for use in agunsight trainer, and to a gunsight trainer for the training ofanti-aircraft gun crews.

Heretofore, a means for controlling the motion of a simulated targetimage within a gunsight trainer, independently of the supportingframework of the trainer, has not been known. The desirability of atrainer incorporating such a means has been recognized, however, for thereason that such a trainer could simulate most effectively theconditions which a prospective gunner might meet in combat, since thetrainee would be unable to exercise any degree of control over themovement of the simu lated target image.

It is therefore one object of the present invention to provide animproved gunsight trainer wherein the trainee operator does not exerciseany degree of control over the movement of a simulated target derivedtherein.

Another object of the invention is to provide a gunsight trainer inwhich motion is imparted to a simulated target image by a movable mirrorthat is situated within the trainer and that is controlled in itsmovement by a precessing gyroscope, the precession of which iscontrolled independently of the trainer framework.

A still further object of this invention is to provide a motionimparting apparatus which comprises a gyroscope and a means for applyinga precessing torque to the gimbal frame of the gyroscope, said torquebeing controlled independently of the housing in which the gyroscope ismounted.

Other objects and many of theattendant advantages of this invention willbe appreciated readily as the same becomes understood by reference tothe following detailed description, when considered in connection withthe accompanying drawings, wherein:

Fig. 1 is a schematic diagram of an entire gunsight trainer system whichconstitutes the present invention; and

Fig. 2 is a perspective drawing showing in detail the construction ofthe novel gyroscope torque applying means, that is partially illustratedin Fig. 1, and which forms a part of the present invention.

Fig. 3 is a perspective drawing showing in detail the target imagemovement linkage mechanism that is partially illustrated in Fig. 1.

Broadly, the present invention constitutes a gunsight trainer in whichthe mechanism for moving the simulated target image is independent ofthe framework of the trainer and consists of three separate units: ananti-aircraft, optical gunsight 1 which derives a reticle image; atarget image 2 that is attached to the gunsight and which comprises ameans for generating a target image and a system of gyro-controlledmirrors for focusing the target image and for imparting movement theretorelative to an eyepiece and to the reticle image; and a target imagemotion control unit 3 for controlling the movement imparted to thetarget image. Though the gunsight l. and the motion control unit 3 areessential to a proper disclosure of the gunsight trainer, their detailsdo not form a part of the present invention and therefore they have beenshown only schematically for the purpose of illustrating their functionin the trainer system.

2 The disturbed computing gunsight A disturbed computing gunsightconsists of a means for automatically inserting a ballistic correctionangle and a proper lead angle between the line of sight of the gunsight,as it tracks a target, and the line of fire of the gun upon which thegunsight is mounted. The gunsight 1 constitutes a disturbed computinggunsight and consists of an image light source 4, a reticle 5, and acollimating lens 6 for creating a reticle image. The reticle image isfocused upon a traverse control mirror 7 which has a lever arm mountedin a U-shaped upright 8 that is keyed to the rotor shaft of a traverserate of swing gyro 7a. The traverse rate of swing gyro 7a is not shown,but has its outer gimbal frame mounted on the gunsight and serves todevelop a turning torque that is proportional to the rate of change ofazimuth of the gunsight, during the tracking operation. The turningtorque, developed by the traverse rate of swing gyro 7a, is transmittedby the proper shafting to the U-shaped upright 8 which rotates themirror 7 by an amount proportional to, and in the same sense as, thetorque developed by the traverse rate of swing gyro; thereby offsettingthe reticle image from the line of fire to a target by a proper leadangle in azimuth. Gyro controlled traverse mirror 7 imposes the reticleimage upon a semi-transmissive elevation mirror 9, which is rotated inelevation by an elevation rate of swing gyro 9a that is substantiallylike the traverse gyro 741 but is different therefrom in that its outputis proportional to the rate of change in elevation of the target beingtracked. The torque developed by the elevation gyro 9a is transmitted tomirror 9 which causes the reticle image to be offset from the line offire to a target by a proper elevation lead angle. Mirror 9 is a 50%reflecting mirror and is in alignment with a sighting window 10 and atarget viewing window 11 so that the gunsight operator, who normallysights through the sighting window 14), has a direct view of the targetwith the reticle image superimposed when the target is being properlytracked.

The present invention in no way modifies the operation of the disturbedcomputing gunsight ll except to provide a movable, false target imagewhich can be controlled independently of the gunsight in place of anactual target. The means for doing this are shown broadly in the targetimage unit 2 and the target motion control unit 3.

The target image uni! Target image unit 2 is attached to the gunsight 1and consists of a target image source 12, a collimating lens 13, a firstreflecting mirror 14- and a second reflecting mirror 15, which serve toderive an imitation target image and to impose the image upon asemi-transmissive, gyro-controlled, movable mirror 16. Semi-transmissivemirror 16 is in alignment with a trainer window 17 and the viewingwindow 11 and elevation mirror 9 of gunsight It so that the reticleimage, that is derived in the gunsight, may he superimposed on theimitation target image depending upgn the relative positions of themirror 16 and the gunsig t It.

Because the target image unit housing 2 is secured to the gunsight 1,some means for moving the mirror 16 independently of the housing 2 isneeded, order to impart motion to the imitation target relative to thegunsight. This means constitutes a part of the present invention andconsists of a double-gimbal gyroscope 21, 18 having a precessing torqueapplying means mounted on the spin axis of the gyroscope for causingsaid gyroscope to precess independently of its housing and a linkagemechanism for conveying the movement of the processing gyroscope tomirror 16.

The construction of the gyroscopic, independent motion-impartingassembly and a preferred manner of mounting the same is best shown inFig. 2 of the drawings, wherein the housing 2 is illustratedschematically as a rectangular frame to which is attached a frame 21.Frame 21 constitutes the outer gimbal frame of the gyroscope and issuspended from the housing 2 by a shaft 22, which is mounted in a freeturning gland 23 that allows the gimbal frame 21 to rotate freely in ahorizontal plane. Rotatably journaled in the outer gimbal frame 21 is ashaft 24, upon which the inner gimbal frame and rotor housing 18 ismounted, in such a manner that rotor housing 18 rotates freely in avertical plane. Fixed to rotor housing 18 is a hollow shaft 25, 26,which constitutes an extension from the spin or rotor axis of thegyroscope, and which has its outer end 26 swivelly mounted on its innerportion 25 by virtue of a swivel joint 28. Shaft 25, 26 also has hole 19in the outer end thereof that serves as an air jet upon air beingsupplied to it from the source of compressed air shown in Fig. 1. Air issupplied to the air jet through a conduit 27, that connects from thesource of compressed air through a free turning gland 23, and a sealedswivel joint 28 that serves both to supply air to the air jet and toallow the outer end 26 of shaft 25, 26 to be rotated about the spin axisof the gyroscope by a synchro motor 20. Synchro motor 20 has its rotorfixed to the outer rotatable end 26 of shaft 25, 26 and its stator fixedto the inner portion of said shaft so that by controlling the thrustproduced by the air jet and the direction in which synchro motor 20rotates the jet, the amount and sense m which the gyroscope precessescan be determined independently of the housing 2. The means forproviding this control will be discussed more fully with relation to thetarget motion control unit.

Actually, as described above, the motion of the air jet and therefore ofthe simulated target image will not be entirely independent of themotion of housing 2. Because of the manner in which the gyroscopeassembly is suspended from housing 2, motion of the housing 2 about itsgyroscope spin axis 25 will result in imparting a corresponding motionto the air jet 19 with reference to the earth. Consequently, thedirection of the torque applied to the gyroscope is in part affected bymotion of the housing 2 about gyroscope spin axis 25. Should it provedesirable to diminish the eifect of any motion of the housing about spinaxis 25, a pendulum assembly 29 and 30 may be added to the mechanismdescribed above. The pendulum assembly is suspended from the innergimbal frame 18 and consists of two parts, a supporting framework 29that is rotatably mounted on rotor shaft extension 25 and a pendulum arm30 which is suspended from the ends of the framework 29. Mounted onframework 29 and aligned with rotor shaft extension 25, in place ofbeing mounted directly on extension 25 as described above, is thesynchro motor 20. Thus, any motion imparted to the housing 2 about spinaxis 25 is taken up by the pendulum assembly, and the air jet remainsfixed relative to the ground.

The linkage mechanism for conveying the movement of the gyroscope tosemi-transmissive mirror 16 is best shown in Fig. 3 of the drawingswherein the outer gimbal frame 21 having one of its vertical sides 31extended to form a support for semi-transmissive mirror 16 is shownsuspended from housing 2. Journaled in the outer gimbal frame 21 is ashaft 24 that supports the inner gimbal frame and rotor housing 18, uponwhich the air jet 19 and synchro motor 20 are mounted. The lower end ofthe extended side 31 is forked to form a bifurcated journal for arotatable shaft, that is secured to a bracket 32 which holds mirror 16,and that causes mirror 16 to rotate in a substantially horizontal planein accordance with the precession of the gyroscope about a substantiallyvertical axis, i. e. the shaft 22; such precession occurring when theair jet 19 produces a couple on the shaft 25 having a component parallelto the shaft 22 tending to rotate the rotor housing 18 about the shaft24. The rotatable shaft is extended through both branches of thebifurcated end section of extension arm 31, and a lever arm 33 is fixedto the shaft between the two sections of the bifurcated end section.Inner gimbal shaft 24 is extended beyond the frame 21 and has a similarlever arm 34 attached to it which is properly aligned with the lever arm33. A connecting rod 35 links the two lever arms together so thatrotation of inner gimbal frame 18 causes mirror 16 to be rotated in asubstantially vertical plane, in accordance with the precession of thegyroscope about a substantially horizontal axis, i. e. the shaft 24;such precession occurring when the air jet 19 produces a couple on theshaft 25 having a component parallel to the shaft 24 tending to rotatethe rotor housing 18 about the shaft 22.

In addition to the imitation target image source and the mirrormoving-assembly described in the two preceding paragraphs, the TargetImage Unit contains a scoring unit for indicating how well the operatortracks the target image. This unit consists of a collimating lens 36which focuses the portions of the reticle and target images that do notpass through 50% reflecting mirror 16 on a mask 37 in front of aphotocell scoring tube 38; mask 37 being positioned so that Whenever thereticle beam is superposed on the target beam, i. e. whenever theoperator is properly tracking the target image, the reticle image passesthrough the mask and falls upon the photocell scoring tube.

Target motion control unit In order to externally control the amount ofturning or precessing torque applied to the inner gimbal frame of thegyroscope by the air jet 19 as well as the direction in which the jet isrotated by synchro motor 20, a target motion control unit 3 isfurnished. The target motion control unit is mounted separately from theTarget Image Unit and the gunsight 1 and comprises a source ofcompressed air 40 which is connected to a cam controlled, regulatingvalve 41. Valve 41 has its valve stem 42 linked to a connecting arm 43that is driven by a rotating cam 44. Cam 44 can be of any desired shapeand is one of a plurality of cams that can be selected by a camselecting apparatus 45 to drive the connecting arm 43. Regulating valve41 regulates the amount of air passing to the air jet 19 through conduit27 in accordance with the shape of the driving cam to thereby cause thegyroscope to precess at a rate which is dependent upon the cam selected.

The direction in which the gyroscope precesses is dependent upon thedirection in which the air jet 19 is rotated by synchro motor 20. Thisdirection is determined by a synchro generator 46 which is electricallyconnected to the synchro motor 20 by conductor 47. Synchro generator 46has its rotor shafted to a flywheel 48 that is linked to a connectingarm 49 and a rotating cam 59 that is one of a second group of selectablecams mounted in the cam selecting assembly 45. The shape of the camselected to drive flywheel 48 determines the direction to which thesynchro system 46, 20 rotates the air jet 19 to thereby provide a meansfor controlling the direction in which the gyroscope precesses.

If desired the air regulating valve 41 and synchro generator 46 may becontrolled manually in place of the grseset-cam control provided by camselecting assembly Operation of the trainer Having described theconstruction of the Gunsight Trainer, its operation is as set forthhereinbelow. As previously described, the gunsight 1 is normally mountedin gimbal frames on a training stand and can be rotated freely in boththe vertical and horizontal planes. The target image unit 2 is mountedon the gunsight with the trainer window 17 and 50% reflecting mirror 16aligned with gunsight window 11 and the gyro-controlled, elevationmirror 9. To operate the trainer, a trainee operator rotates the entireassembly consisting of gunsight 1 and the image unit 2 about the standupon which they are mounted while tracking the target image. Themovement of the target image is controlled by an instructor who operatesthe target motion control unit. The instructor controls the movementimparted to the target image by operating the cam selecting apparatus 45or alternatively manually controlling the air supply regulating valve 41and synchro motor 46. As the instructor causes the target image to bemoved relative to the eyepiece 17, the trainee operator swings thetrainer assembly 2 and 3 in azimuth and in elevation, to thereby trackthe movement of the target image. The skill with which this operation isperformed is recorded by the photocell scoring unit 36, 37 and 38.

Having described the present invention and its operation, obviously manymodifications and variations are possible in the light of the aboveteachings. It is therefore to be understood that within the scope of theappended claims the invention may be practiced otherwise than asspecifically described.

What is claimed is:

1. A target simulator for attachment to an optical gunsight to provide amoving target image in the field of view of the gunsight, comprising, ahousing, means supported by said housing for providing a simulatedtarget image, a gyroscope having a rotor, an outer gimbal frame and aninner gimbal frame, a vertical axle supported by said housing, saidouter gimbal frame being rotatably mounted on said vertical axle, ahorizontal spindle rotatably supported by said outer gimbal frame, saidinner gimbal frame being mounted on said horizontal spindle, asemi-transmissive mirror pivotally mounted on said outer gimbal frameand upon which said target image is imposed, a mechanical linkageconnecting said mirror with said spindle to transmit the rotation ofsaid inner gimbal frame to said mirror, a shaft aligned with the rotoraxis of said gyroscope and supported by said inner gimbal frame, an airjet rotatably mounted on said shaft for applying a torque perpendicularto said rotor shaft, and a synchro motor having its stator fixed to saidshaft and its rotor fixed to said rotatable air jet, whereby saidgyroscope is caused to process to move said target image relative to andindependently of the gunsight,

2. A target simulator as set forth in claim 1, further characterized bya reservoir of compressed air, and means for supplying compressed airfrom said reservoir to the air jet at a varying rate.

3. A target simulator as set forth in claim 1, further characterized bya synchro generator for energizing the synchro motor and means forselectively and variably positioning the rotor of said synchro generatorto correspondingly turn the rotor of said synchro motor.

4. A target simulator for attachment to an optical gunsight to provide amoving target image in the field of View of the gunsight, comprising, ahousing, means supported by said housing for providing a simulatedtarget image, a gyroscope having a rotor, an outer gimbal frame and aninner gimbal frame, a vertical axle supported by said housing, saidouter gimbal frame being rotatably mounted on said vertical axle, ahorizontal spindle rotatably supported by said outer gimbal frame. saidinner gimbal frame being mounted on said horizontal spindle, asemi-transmissive mirror pivotally mounted on said outer gimbal frameand upon which said target image is imposed, a mechanical linkageconnecting said mirror with said spindle to transmit the rotation ofsaid inner gimbal frame to said mirror, a shaft aligned with the rotoraxis of said gyroscope and supported by said inner gimbal frame, an airjet rotatably mounted on said shaft for applying a torque perpendicularto said rotor shaft, supporting means mounted on said shaft andmaintaining a vertical position with relation to the earth, and asynchro motor having its stator fixed to said supporting means and itsrotor connected to said rotatable air jet for rotating said air jet.

5. A target simulator as set forth in claim 4, wherein the supportingmeans includes a framework rotatably mounted on the shaft, and apendulum suspended from said frame Work.

6. A gunsight trainer, comprising, an optical gunsight having a sightingwindow through which the reticle image derived therein can be seen, andan arrangement fixed to said gunsight for providing an imitation targetimage and for causing said imitation target to move relative to andindependently of said gunsight, said arran ement com rising a housingmounted upon said gunsight and having a viewing window which is ali nedwith said gunfight-sighting window and through which said gun-sightreticle image can be observed, a movable, semi-transmissive mirrorsuspended within said housint: in the line of sight between said viewingand sighting windows, an imitation target image source, means forimposing said target image on said semi-transmissive mirror, meansmoving said mirror relative to and independently of said gunsight andhousing including a gyroscope having an outer gimbal frame and an innergimbal frame, said outer gimbal frame being rotatably supported by saidhousing so as to rotate freely in a horizontal plane, a shaft alignedwith the rotor axis of said gyroscope and mounted on said inner gimbalframe, means rotatably mounted on said shaft for applying a torqueperpendicular to said rotor axis, means for rotating said torque aplying means about said shaft, and means for transmitting the motionproduced upon precession of said gyroscope to said movable mirror.

7. A gunsight trainer, comprising, an optical gunsight having a sightingwindow through which the reticle image derived therein can be seen, andan arrangement fixed to said gunsight for providing an imitation targetimage and for causing said imitation target to move relative to andindependently of said gunsight, said atrangement comprising a housingmounted upon said gunsight and having a viewing window which is alignedwith said gunsight-sighting window through which said gunsight reticleimage can be observed, a movable, semi-transmissive mirror suspendedwithin said housing in the line of sight between said viewing andsighting windows, an imitation target image source, means for imposingsaid target image on said semi-transmissive mirror, means for movingsaid mirror relative to and independently of said gunsight and housingincluding a gyroscope having an outer gimbal frame and an inner gimbalframe, said outer gimbal frame being rotatably supported by said housingand free to rotate in a horizontal plane, a shaft mounted on said innergimbal frame and aligned with the rotor axis of said gyroscope, a torqueapplying means rotatably mounted on said shaft, means for rotating saidtorque applying means about said shaft. means for transmitting themotion produced by precession of said gyroscope to said movable mirror,and a pendulum assembly suspended from the inner gimbal frame of saidgyroscope.

8. A gunsiizht trainer, comprising, an optical gunsight having asighting window through which the reticle image derived therein can beseen, and an arrangement fixed to said gunsiqht for providing animitation target image and for causing said imitation target to moverelative to and independently of said gunsight, said arrangementcomprising a housing mounted upon said gunsiuht and having a viewingwindow which is aligned with said gunfight-sighting window and throughwhich said gunsiaht reticle image can be observed, a movable,semitransmissive mirror suspended Within said housing in the line ofsight between said viewing and sighting windows, an imitation targetimage source, means for imposing said target image on saidsemi-transmissive mirror, means for moving said mirror relative to andindependently of said gunsight and housing including a gyroscope havingan outer gimbal frame and an inner imbal frame, said outer gimbal framebeing rotatablv supported by said housing so as to rotate freely in a hrizontal plane, a shaft aligned with the rotor axis of said gyroscopeand mounted on said inner gimbal frame, an air jet rotatably mounted onsaid shaft, and a svnchro motor having its stator mounted on said shaftand its rotor fixed to said r tatable air jet for controlling thedirection in which said air jet reacts.

9. A target simulator for attachment to an optical gn sight to provide amoving target in the field of vi 1 of said optical gunsight, comprising,a housing, a target image source supported by said housing, a gyroscopehaving a rotor, an outer gimbal frame and an inn r gimbal framerotatably sup orted bv said outer gimbal frame, said outer gimbal framebe ng rotatably supported by said housing, a semi-transmissive mirror upn which is imposed the target image derived fr m said target imagesource, said mirror being pivotally mounted on said outer gimbal frameand in the field of vie of said gunsight, a shaft aligned with the rotoraxis of said gyroscope and sup orted by said inner imbal frame. air jetmeans rotatably mounted n. sa d sh ft for ap lying a tor ueperpendicular to said shaft, and a synchro motor having its stat r fixedto the shaft its rotor fixed to said rotatable air jet means forrotating said air jet means about said shaft, thereby causing saidgyroscope to precess and said image to move relative to andindependently of said gunsight.

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